Standard SSL certificates can be used with one hostname. UC certificates are generally used with Microsoft Exchange Server 2007 and 2010, however they can be used with any web server type to secure multiple, distinct hostnames with one certificate using the certificate “Subject Alternate Name” field.

The certificate Subject Alternative Name field allows you to create a certificate that is valid for multiple hostnames, including both internal system names and externally resolvable domain names.

What can you do with Subject Alternative Names?

Secure host names on different base domains in one SSL Certificate. A wildcard certificate can protect all first-level subdomains on an entire domain, such as *.example.com. But a wildcard cannot protect both www.example.com and www.example.net.

Host Multiple SSL sites on a single IP address. Hosting multiple SSL-enabled sites on a single server typically requires a unique IP address per site, but a certificate with Subject Alternative Names can solve this problem. Microsoft IIS 6 and Apache are both able to host multiple HTTPS sites using SAN certificates also known as Unified Communications SSL.

Greatly simplify your Exchange Server 2007 SSL configuration. Using a SAN certificate saves you the hassle and time involved in configuring multiple IP addresses on your Exchange 2007 server, binding each IP address to a different certificate, and running a lot of low level PowerShell commands just to piece it all together.

Where can you see Subject Alternative Names in action?

To see an example of Subject Alternative Names, click the padlock in your browser to examine our SSL certificate. In the certificate details you will find a Subject Alternative Name extension that lists any Subject Alternative Names.